JavaScript: Comments

In addition to code, source files can contain comments. This is text that is not part of the program and is used by programmers for notes. They are used to add explanations of how the code works, what bugs need to be fixed here, or as reminders to add something later.

// Remove the line below after implementing the registration task
console.log(10);

There are two types of comments in JavaScript:

Single-line comments

Single-line comments start with //. After these two characters, any text can follow; the entire line will not be analyzed or executed.

A comment can take up the whole line. If one line is not enough, several comments are created:

// For Winterfell!
// For Lanisters!

A comment can be placed on a line after some code:

console.log('I am the King'); // For Lannisters!

Multi-line comments

Multi-line comments start with /* and end with */.

/*
  The night is dark and
  full of terrors.
*/
console.log('I am the King');

Such comments are usually used for documenting code, for example, functions.

Service comments

While working, you will encounter such code in our editor:

// BEGIN

// END

BEGIN and END here are ordinary comments that do not affect the program in any way. They show where to write the code for the task.

// BEGIN
<your solution here>
// END

When you see BEGIN and END, write your code between them and leave the rest unchanged.

You are writing a program and realize that one part needs to be finished later. To avoid forgetting, programmers leave notes for themselves right in the code — TODO comments.

Add such a comment to the file:

// TODO: add a greeting function

When you come back to this place later, the comment will remind you that there is still unfinished work here.